Prevention of concrete cracks has been a headache for architects for many years. Huge amounts of money have been spent year by year for their repair.
Concrete is basically a brittle material. It shrinks from slurry state to solid state during curing. Since concrete is easily affected by the change of surrounding temperature, outside force and pressure during curing stage, cracking thereof is almost unavoidable.
Cracking will cause the concrete to become brittle due to neutralization. The rigidity and strength will deteriorate and finally the entire structure is damaged.
Heretofore, mortar is often used to provide protection against cracking or other rupture of concrete. Mortar is, however, not strong enough in its physical properties to prevent the cracking perfectly.
Meanwhile, iron reacts with oxygen in the air, and other materials (chlorine, fluorine, sulfurous acid gas), and also bacteria, causing corrosion and rusting.
For preventing such corrosion and rusting of the iron or other metals, conventionally, various surface coating agents have been developed as surface coating agents for metals, especially iron.
However, the difference in expansion temperature rate between a metallic substrate and the coating agent has caused degradation of the coating and shortening of its service life.
Furthermore, certain surface coating agents are applied to plastics for added resistance to weathering. Again, the resulting films are not durable; they rarely adhere securely and permanently to the substrate and will easily peel off.
Among various surface coating agents, organic solvent type coating agent gives relatively good adherence and durability but presents problems of environmental pollution with the solvent evaporated in the course of application.
Emulsion type of coating agents, on the contrary, cause less environmental contamination, but the coating films are inferior in both adherence and durability. In addition, they can corrode the substrate, when the latter is metallic.
Accordingly, it is an object of the present invention is to provide a surface coating agent capable of forming highly adherent, durable, corrosion-resistant coating films adapted for universal use on varied surfaces without deteriorating the substrate.
It is another object of the present invention to provide various methods for effectively using the above surface coating agent.